Depressor labii inferioris muscle

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Depressor labii
Depressor labii inferioris.png
Muscles of the head, face, and neck.
Details
Origin oblique line of the mandible, between the symphysis and the mental foramen
Insertion integument of the lower lip, Orbicularis oris fibers, its fellow of the opposite side
Nerve marginal mandibular branch of the facial nerve
Actions depression of the lower lip
Antagonist orbicularis oris muscle
Identifiers
Latin musculus depressor labii inferioris
TA98 A04.1.03.033
TA2 2083
FMA 46816
Anatomical terms of muscle

The depressor labii inferioris (or quadratus labii inferioris) is a facial muscle. It helps to lower the bottom lip.

Contents

Structure

The depressor labii inferioris muscle arises from the lateral surface of the mandible. [1] This is below the mental foramen, and the origin may be around 3 cm wide. [1] It inserts on the skin of the lower lip, blending in with the orbicularis oris muscle around 2 cm wide. [1] At its origin, depressor labii is continuous with the fibers of the platysma muscle. Some yellow fat is intermingled with the fibers.

Nerve supply

The depressor labii inferioris muscle is supplied by the marginal mandibular branch of the facial nerve. [1] [2]

Function

The depressor labii inferioris muscle helps to depress and everts the lower lip. [1] It is the most important of the muscles of the lower lip for this function. [1] It is an antagonist of the orbicularis oris muscle. [1] It is needed to expose the mandibular (lower) teeth during smiling. [1]

Clinical significance

Resection

The depressor labii inferioris muscle may be resected (cut and removed) using surgery to correct an asymmetry of the lower lip when smiling. [1] This asymmetry can be caused by paralysis of the marginal mandibular branch of the facial nerve on one side, so the healthy side may be cut to create symmetry. [1] Local anaesthesia may be used, such as by blocking the mental nerve. [1] This operation tends to be successful. [1]

History

The depressor labii inferioris muscle has also (mainly historically) been called the quadratus labii inferioris muscle. [1]

See also

Additional images

Related Research Articles

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Orbicularis oris muscle

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Lip Visible body part at the mouth

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Platysma muscle Human neck muscle

The platysma muscle is a superficial muscle of the human neck that overlaps the sternocleidomastoid. It covers the anterior surface of the neck superficially. When it contracts, it produces a slight wrinkling of the neck, and a "bowstring" effect on either side of the neck.

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Levator labii superioris

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Mentalis Muscle that raises the central portion of the lower lip

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Depressor anguli oris muscle Facial muscle that depresses the corner of the mouth during frowning

The depressor anguli oris muscle is a facial muscle. It originates from the mandible and inserts into the angle of the mouth. It is associated with frowning, as it depresses the corner of the mouth.

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Mental foramen Opening on the anterior aspect of the mandible through which the mental nerve and vessels exit

The mental foramen is one of two foramina (openings) located on the anterior surface of the mandible. It is part of the mandibular canal. It transmits the terminal branches of the inferior alveolar nerve and the mental vessels.

Mental nerve

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Marginal mandibular branch of the facial nerve

The marginal mandibular branch of the facial nerve passes forward beneath the platysma and depressor anguli oris, supplying the muscles of the lower lip and chin, and communicating with the mental branch of the inferior alveolar nerve.

Buccal branches of the facial nerve

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Submental artery

The submental artery is a branch of the facial artery that runs on the underside of the chin.

Facial muscles

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Jaw reduction or Mandible angle reduction is a type of surgery to narrow the lower one-third of the face—particularly the contribution from the mandible and its muscular attachments. There are several techniques for treatment—including surgical and non-surgical methods. A square lower jaw can be considered a masculine trait, especially in Asian countries. As a result, whereas square lower jaws are often considered a positive trait in men, a wide mandible can be perceived as discordant or masculine on women, or sometimes in certain men, particularly when there is asymmetry.

Mandible Lower jaw bone

In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone of the skull. It is connected to the temporal bones by the temporomandibular joints.

References

PD-icon.svgThis article incorporates text in the public domain from page 383 of the 20th edition of Gray's Anatomy (1918)

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 Hussain, G; Manktelow, R.T; Tomat, L.R (September 2004). "Depressor labii inferioris resection: an effective treatment for marginal mandibular nerve paralysis". British Journal of Plastic Surgery . 57 (6): 502–510. doi:10.1016/j.bjps.2004.04.003. ISSN   0007-1226 via ScienceDirect.
  2. Tapiwa Mabvuure, Nigel; Pinto-Lopes, Rui; Bolton, Lauren; Tzafetta, Kallirroi (August 2021). "Lower lip depressor reanimation using anterior belly of digastric muscle transfer improves psychological wellbeing in facial palsy patients". British Journal of Oral and Maxillofacial Surgery. doi:10.1016/j.bjoms.2021.07.025. ISSN   0266-4356.